The levels of psychoactive chemicals tetrahydrocannabinol (THC) and cannabidiol (CBD) are identical across cannabis strains, despite street names and rumours, according to a new study.

Stories behind the unusual names given to street strains of cannabis have been tackled by the research from the University of British Columbia (UBC).

However, the typical chemical levels used to differentiate strains may not indicate their true pharmacological value, the studies suggest.

“It is estimated that there are several hundred or perhaps thousands of strains of cannabis currently being cultivated,” said Professor Susan Murch, who teaches chemistry at the university’s Okanagan campus.

“We wanted to know how different they truly are, given the variety of unique and exotic names.”

Although cannabis farmers and strain developers have historically selected breeding plants based on their production of THC and CBD, there are limited records of strain parentage.

Professor Murch explained: “People have had informal breeding programmes for a long time.

“In a structured programme we would keep track of the lineage, such as where the parent plants came from and their characteristics.

“With unstructured breeding, which is the current norm, particular plants were picked for some characteristic and then given a new name.”

Image:Informal cannabis breeding undermines analysis of chemicals

Due to the informal breeding, the chemical breakdown of many of these strains has been practically unknown – until now.

Researchers analysed the cannabinoid, a class of psychoactive chemical compounds including THC and CBD, of 33 strains from five licensed cannabis producers.

Their research revealed that most strains, despite their origins and names, had identical or near-identical levels of THC and CBD.

Breeding highly potent strains of cannabis does impact the genetic diversity within the crop, but not the levels of THC or CBD within the plants themselves.

But according to Elizabeth Mudge, a doctoral student working with Professor Murch, there were observable differences in a number of previously unknown cannabinoids – and these newly discovered compounds, present in low quantities, could be related to pharmacological effects and even serve as a source for new medicines.

Ms Mudge said: “A high abundance compound in a plant, such as THC or CBD, isn’t necessarily responsible for the unique medicinal effects of certain strains.

“Understanding the presence of the low abundance cannabinoids could provide valuable information to the medical cannabis community.”

Image:CBD and THC may not be the most important chemicals in cannabis plants

At the moment, licensed producers in Canada are only required to report the THC and CBD levels in their produce, but Ms Mudge said the new research highlights how other distinguishing chemicals should be analysed too.

She said that while patients are using medicinal cannabis for a variety of reasons, there’s actually very little information available to them to help distinguish strains.

The research published in Scientific Reports is a “first step towards establishing an alternative approach to classifying medical cannabis and providing consumers with better information”, the researchers added.